FGFR2 and acrocephalosyndactyly: Among bone cell metabolic pathways in which tryptophan is involved, Lemonnier et al., 2000 [19], have demonstrated that in Apert Syndrome, a form of acrocephalosyndactyly characterized by premature ossification and fusion of cranial sutures, the origin of the pathology is the Ser252Trp mutation of the fibroblast growth factor receptor FGFR2.